Fig. 4. Expression of Ccn2 and follistatin is induced by Eda-A1. Eda-deficient (A,B) or wild-type (C) E14 individual skin explants were cut in two halves along the midline and cultured in the absence or presence of 2 µg/ml Eda-A1, and gene expression was analysed by quantitative RT-PCR. (A) A timecourse of expression of Ccn2, Smad7, follistatin and I-B in Eda-deficient skin upon Eda-A1 stimulus. Upregulation of Ccn2 is detected already after 1 hour of Eda treatment and peaks at 3-4 hours. I-B is induced with kinetics similar to Ccn2. (B) Comparison of Ccn2 induction by Eda-A1 in skin explants cultured in a medium with or without serum. Ccn2 transcripts are maintained at high level for a longer time in the absence of serum. (C) Induction of Ccn2, Smad7 and follistatin gene expression in wild-type skin after exposure to Eda-A1 in the absence of serum.